1. Field of the Invention
The present invention relates to an off-line teaching method and an apparatus for the same to be used to operate a plurality of robot models displayed on a monitor by using a keyboard or a pointing device (for example, a mouse), wherein an application corresponding to a designated robot model can be easily started, and mutual interlock, which is effected when a plurality of robot models are operated, can be easily reflected on teaching data.
2. Description of the Related Art
Recently, in order to apply a robot to a variety of workings, in general, a variety of tools are attached to a face plate of a robot arm to allow the robot to perform the tasks.
The programming for the robot includes the on-line programming (on-line teaching) and the off-line programming (off-line teaching). In the case of the on-line teaching, the arm of the robot is moved to pass through necessary points or along a locus by using a push button, an operation button, an operation handle, and a joystick so that the control unit is allowed to store the points or the locus. When the robot is operated at the driving stage, the robot reproduces and executes the stored movement.
In the off-line teaching, the operation procedure is programmed without directly using the robot. In the case of the off-line teaching, the software is programmed such that the movement of each joint is calculated in order to move the end effector to a necessary position in a necessary direction.
The movement of the robot can be displayed in animation on a graphic terminal connected to a computer, by adding a graphic function to the system which is used to execute the off-line teaching. The off-line teaching based on the use of the graphic has the following advantages.
(1) When the operation program is debugged by using the graphic, it is possible to reduce the time and the labor as compared with a case in which an actual robot is used.
(2) It is possible for the user to begin programming before the robot is introduced. Further, various types of robots can be tested on the monitor screen to select a type of machine which is most suitable for the plan.
(3) It is possible to avoid conflict in view of surrounding situations when the movement of the robot is simulated.
(4) It is possible to use a common database of CAD/CAM. For example, when a computer for CAD/CAM stores a body shape of an automobile, the designer can designate the place to be subjected to spot welding.
In recent years, a technique has been suggested, in which an image of a teaching box corresponding to an actual robot is displayed on a monitor, and the point is designated by using a mouse or the like for the image of the teaching box to prepare off-line teaching data thereby (for example, Japanese Laid-Open Patent Publication No. 5-173626).
In this suggested illustrative technique, for example, as shown in FIG. 17, a plurality (four in the drawing) of robot models RM1 to RM4 are displayed on a screen of a monitor 200, and program numbers of teaching applications corresponding to the respective robot models RM1 to RM4 are simultaneously displayed on an upper-left portion of the screen. Images of teaching boxes TB1 to TB4 corresponding to the respective robot models RM1 to RM4 are displayed on an upper-right portion on the screen.
The type of the robot model to be subjected to teaching is judged by an operator, and a teaching box corresponding to the type is designated by using a mouse or the like. After that, a program number corresponding to a necessary teaching application is designated from the program numbers arranged in the selection menu by using the mouse or the like. Thus, the concerning teaching application is started.
In this case, when a plurality of types of robot models exist in an identical station in a mixed manner, it is necessary to perform a complicated operation for selecting the teaching application which is required for the robot model to be subjected to the teaching. Therefore, the starting operation takes much time and labor if the operator is not accustomed to the off-line teaching system. As a result, an inconvenience arises in that it is impossible to perform the operation with ease.
On the other hand, when a plurality of actual robots are installed at the working site, it is necessary to prepare the off-line teaching data considering the mutual interlock among the actual robots. Conventionally, a simulation program including mutual interlock has been prepared by editing a text-based program by using an editor.
In such a procedure, it is necessary to perform teaching simulation including mutual interlock actually executed by an operator for an actual robot. Therefore, it has been difficult to handle the system unless the operator is specially educated, or unless the operator knows details of the system.